It's amazing how these (and their remakes) are literally the only games in the series with decent dungeon design. Pretty much each one has something unique about it that keeps it fun.

>first one is just your standard simple cave
>second one is another cave but it's dark and you either need to navigate it mostly blind or explore around and find the HM
>game corner hideout has spin tile puzzle
>silph co has teleportation tile puzzle
>power plant has completely unique encounter tables, offers a legendary, has faux pokeballs
>seafoam islands has some unique encounters, offers a legendary, has a unique strength puzzle to stop water current
>mansion has statue switch puzzle, has completely unique encounter tables
>victory road has a strength switch puzzle, offers a legendary

The problem with the shitty dunjuns in later games is that too many of them fall into the trap of just being a generic HM spam cave with shitty encounters. Sinnoh is the most guilty of this. There are like 5 generic caves in the region and they ALL have Geodude/Machop/Zubat spam. The only one that's well designed is the optional one beneath Cycling Road that has the unique bike mechanics and leads to Gible.